From f8ac760f69de8905c6ff57527baf46e06dad67a4 Mon Sep 17 00:00:00 2001
From: "Gerasimos (Makis) Maropoulos" <kataras2006@hotmail.com>
Date: Sun, 16 Aug 2020 18:37:00 +0300
Subject: [PATCH] i18n: subdomain code: set from cookie if settings allow it,
 so multiple subdomain redirections can set the language correctly instead of
 falling back to the default one

---
 i18n/i18n.go | 20 ++++++++++++++++++--
 iris.go      |  2 +-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/i18n/i18n.go b/i18n/i18n.go
index 945e822d..dde5d76b 100644
--- a/i18n/i18n.go
+++ b/i18n/i18n.go
@@ -405,6 +405,22 @@ func (i *I18n) GetMessage(ctx *context.Context, format string, args ...interface
 	return ""
 }
 
+func (i *I18n) setLangWithoutContext(w http.ResponseWriter, r *http.Request, lang string) {
+	if i.Cookie != "" {
+		http.SetCookie(w, &http.Cookie{
+			Name:  i.Cookie,
+			Value: lang,
+			// allow subdomain sharing.
+			Domain:   context.GetDomain(context.GetHost(r)),
+			SameSite: http.SameSiteLaxMode,
+		})
+	} else if i.URLParameter != "" {
+		r.URL.Query().Set(i.URLParameter, lang)
+	}
+
+	r.Header.Set(acceptLanguageHeaderKey, lang)
+}
+
 // Wrapper returns a new router wrapper.
 // The result function can be passed on `Application.WrapRouter/AddRouterWrapper`.
 // It compares the path prefix for translated language and
@@ -437,7 +453,7 @@ func (i *I18n) Wrapper() router.WrapperFunc {
 
 				r.RequestURI = path
 				r.URL.Path = path
-				r.Header.Set(acceptLanguageHeaderKey, lang)
+				i.setLangWithoutContext(w, r, lang)
 				found = true
 			}
 		}
@@ -450,7 +466,7 @@ func (i *I18n) Wrapper() router.WrapperFunc {
 						host = host[dotIdx+1:]
 						r.URL.Host = host
 						r.Host = host
-						r.Header.Set(acceptLanguageHeaderKey, tag.String())
+						i.setLangWithoutContext(w, r, tag.String())
 					}
 				}
 			}
diff --git a/iris.go b/iris.go
index e16a3c2a..f86555d5 100644
--- a/iris.go
+++ b/iris.go
@@ -531,7 +531,7 @@ func (app *Application) Build() error {
 	if app.I18n.Loaded() {
 		// {{ tr "lang" "key" arg1 arg2 }}
 		app.view.AddFunc("tr", app.I18n.Tr)
-		app.Router.AddRouterWrapper(app.I18n.Wrapper())
+		app.Router.PrependRouterWrapper(app.I18n.Wrapper())
 	}
 
 	if n := app.view.Len(); n > 0 {